对于最终用户来说，数据库系统的体系结构应划分为

A．外模式、概念模式和内模式结构

B．单用户结构、主从结构和分布式结构

C．模型、模式和视图

D．关系结构、网状结构和层次结构

It took _____ building supplies to construct these energy-saving houses. It took brains, too. [ ]

A. other than

B. more than

C. rather than

D. less than